In drill strings used to drill petroleum wells, one or more drill collar sections are usually provided in the string immediately above the drill bit. The drill collars are connected in the drill string and to the drill bit by threaded connections. In order that the drilling will proceed in a controlled manner, the drill collars must be stabilized to be made concentric in the drill hole and to minimize wobble of the drill bit. Stabilization of the drill collars is accomplished by connecting stabilizing devices spaced along the drill collars. It is desirable that the stabilizing devices be adapted to be affixed to the drill collars anywhere along their lengths. Accordingly, the stabilizers are usually clamped to the drill collars without means assisting the clamping provided at the drill collar exteriors.
The drill collars are in the form of elongate tubes or pipes having threaded connection means at each end. Each stabilizer is disposed around the drill collar, intermediate its length, and firmly clamped to the drill collar in a manner to resist longitudinal and rotational movements of the stabilizer. To be satisfactory in use, the stabilizers must be adapted for quick connection to the drill collar and for quick disconnection and movement along the length of the drill collar for reconnection at another location.